Systematic phase control of periodic mesoporous organosilicas using Gemini surfactants
作者:Hyung Ik Lee、Chanho Pak、Seung Hwan Yi、Jeong Kuk Shon、Sung Soo Kim、Byung Guk So、Hyuk Chang、Jae Eui Yie、Young-Uk Kwon、Ji Man Kim
DOI:10.1039/b507225e
日期:——
Highly ordered periodic mesoporous organosilica (PMO) materials with various mesostructures, including lamellar, bicontinuous cubic Ia3d, 2D hexagonal (P6mm), 3D hexagonal (P63/mmc) and cubic Pm3n, have been synthesized using Gemini surfactants with general formulas of [CnH2n+1N(CH3)2(CH2)sN (CH3)2CnH2n+1]Br2
(n
= 6–18 and s
= 3–12, Cn-s-n). The nature of the Gemini surfactant such as alkyl chain length (n) and spacer length (s), and the synthetic conditions such as reaction temperatures and molar compositions are controlling parameters for desired mesostructures. The PMO materials, synthesized at room temperature from Cn-6-n, exhibit phase transition from lamellar to bicontinuous cubic Ia3d, 2D hexagonal, 3D hexagonal and cubic Pm3n as the chain length decreases, whereas only the lamellar and 2D hexagonal PMO materials with different lattice parameters depending on the chain length are obtained at high reaction temperature (373 K). The Cn-8-n and Cn-10-n surfactants also yield 2D hexagonal PMO material in a very wide range of synthetic condition at 373 K. The PMO materials with various mesostructures thus obtained exhibit high BET surface areas in the range of 900–1500 m2 g−1 and total pore volumes of about 0.5–1.4 cm3 g−1.
高度有序的周期性介孔有机硅材料(PMO),包括层状、双连续立方Ia3d、二维六方(P6mm)、三维六方(P63/mmc)和立方Pm3n等不同介观结构,已经使用具有一般公式[CnH2n+1N(CH3)2(CH2)sN(CH3)2CnH2n+1]Br2的双子表面活性剂(n=6-18,s=3-12,Cn-s-n)合成。双子表面活性剂的性质,如烷基链长度(n)和间隔长度(s),以及合成条件,如反应温度和摩尔组成,是控制所需介观结构的关键参数。在室温下,从Cn-6-n合成的PMO材料,随着链长的减少,经历了从层状到双连续立方Ia3d、二维六方、三维六方和立方Pm3n的相转变,而在高温反应(373 K)下,只能得到具有不同晶格参数的层状和二维六方PMO材料,这取决于链长。Cn-8-n和Cn-10-n表面活性剂在373 K的宽泛合成条件下也产生二维六方PMO材料。这些具有不同介观结构的PMO材料,其BET表面积在900-1500 m2 g−1范围内,总孔体积约为0.5-1.4 cm3 g−1。